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Scaling

5 minutes 5 Questions

Scaling is the ability of the Crystal Methods to adapt to projects of varying sizes, complexities, and team compositions. Different project situations call for different Crystal Method variants, but they all adhere to the same core principles. These variations, such as Crystal Clear, Crystal Orange…

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Agile Project Management - Scaling Example Questions

Test your knowledge of Scaling

Question 1

An e-commerce application runs on EC2 instances, with orders stored in an Amazon RDS database. During the holiday season, traffic increases dramatically. What can be done to ensure the application remains responsive during this time?

Correct Answer: Use Auto Scaling groups, ELB, and RDS Read Replicas.

Using Auto Scaling groups, Elastic Load Balancing (ELB), and RDS Read Replicas ensures that both the application and database layers scale to accommodate increased traffic. Other options may be less effective or introduce additional complexity.

Question 2

An Auto Scaling group behind an Application Load Balancer scales out during traffic spikes. New instances take a few minutes to initialize and frequently fail health checks during this warm-up, causing the Auto Scaling group to terminate them and resulting in downtime. What configuration change would most effectively minimize downtime and prevent premature termination of new instances during spikes?

Correct Answer: Increase the Auto Scaling group's health check grace period so new instances have time to initialize before health checks can fail.

When an Auto Scaling group uses load balancer health checks, newly launched instances may take time to bootstrap (install packages, start services, warm caches). If health checks run immediately, these instances can be marked unhealthy and terminated before they are ready, causing churn and downtime during spikes. The health check grace period delays health evaluations for a specified time after instance launch, preventing premature termination and giving instances time to become healthy. Alternatives like increasing cooldowns or launching more instances per step do not prevent premature health-check failures. Changing instance type or manual scaling does not address the root cause of termination during warm-up.

Question 3

A gaming company is using a fleet of EC2 instances for its multiplayer servers. The user base varies throughout the day, and the company wants to optimize costs while maintaining a reliable gaming experience. Which EC2 purchasing option is best suited for this use case?

Correct Answer: EC2 Spot Instances.

EC2 Spot Instances provide the most cost-effective and scalable option for a fleet of instances with variable user base. While other instances work in varying scenarios, they lack the cost efficiency of Spot Instances for this specific use case.

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